Jim Simons' Renaissance drops $520 million on surging tech stock

Renaissance Technologies just made a major statement with its latest 13F release, with a massive bet on red-hot Micron (MU) stock. The quant powerhouse founded by the late Jim Simons raised its stake in the memory giant by more than 50%, adding nearly 1.81 million shares, at about $520 million in new exposure based on year-end prices.That brings its total position to nearly $859 million, making Micron a top-tier holding for the fund.It also comes in a quarter when Renaissance cut back its stake in AI bellwether Nvidiaand Google-parent Alphabet.Micron has arguably been one of the best-performing tech stocks lately, with investors laughing all the way to the bank.For perspective, Micron stock is up 231% over the past six months and more than 73% over the past three.The massive bet comes at an opportune time, as memory markets shift from a glut to a tightening supply. Prices have climbed, and Micron’s guidance suggests margins could jump through 2026. That has everything to do with AI and the relentless demand for high-bandwidth memory (HBM), which has become the most supply-constrained, yet strategically critical, part of the chip world.Renaissance’s move suggests it’s betting heavily on memory prices, potentially leading to returns that are more outsized than many investors expect. Renaissance Technologies boosted Micron stake by roughly $520 million in its latest 13F filing.Photo by Sylvain Gaboury on Getty Images Renaissance's latest 13F activity snapshotMarket value:$64.5 billion (prior $75.8 billion)Inflows/(outflows) as % of total market value:-14.9%New purchases:466 stocksAdded to:1,030 stocksSold out of:738 stocksReduced holdings in:1,680 stocksTop 10 holdings concentration: 12.1%. Source: WhaleWisdom Who was the late Jim Simons?Jim Simons is best described as a mathematician-turned-market-disrupter who, in many ways, redefined investing.Simons founded Renaissance Technologies in 1978, favoring data-driven decision-making over instincts and trading at scale.Breaking from the crowd, he hired mathematicians and codebreakers, flipping the traditional script of hiring stock-pickers.Under his leadership, Renaissance’s flagship Medallion Fund became the stuff of legend, averaging more than 60% annually for 30 years, according to Reuters. Renaissance itself grew into a behemoth, with assets under management jumping to over $106 billion in 2024, according to Investopedia. This included nearly $10 billion in the Medallion Fund, which is famously closed to the public.More AI Stocks:Morgan Stanley sets jaw-dropping Micron price target after eventBank of America updates Palantir stock forecast after private meetingMorgan Stanley drops eye-popping Broadcom price targetIn 2008 alone, Medallion gained nearly 82% in value, according to Firstlinks, while the S&P 500 tanked.Simons stepped down as CEO in 2010 and left the chairmanship in 2021. He passed away a few years later on May 10, 2024, at age 86, Reuters reported. Forbes estimated his net worth at around $31 billion. Currently, Renaissance is run by Peter Brown, per Reuters. Brown, a longtime executive, is also the firm’s CEO.Renaissance’s biggest 13F shiftsTop buys (largest value)Costco: $0.59 billionMicron Technology: $0.52 billionTesla: $422 millionNetflix: $419 millionProcter & Gamble: $313 million Source: WhaleWisdom Top sells (largest value)Nvidia: $0.89 billionAlphabet (Class A): $0.72 billionAlphabet (Class C): $0.51 billionAppLovin: $460 millionGilead Sciences: $328 million Source: WhaleWisdom Top holdings (percent of portfolio)Palantir Technologies: 2.43%United Therapeutics: 1.44%Micron Technology: 1.33%Kinross Gold: 1.09%VeriSign: 1.05% Source: WhaleWisdom Renaissance makes an early-cycle bet on Micron stockMicron has been the pick of the tech stocks over the past few months, spearheaded by a relentless AI-driven memory cycle.The numbers back that up.In fiscal 2025, data-center sales skyrocketed to 56% of total sales, with 52% gross margins. Fiscal Q4 HBM sales hit roughly $2 billion, with a nearly $8 billion annualized run rate.Related: Legendary billionaire investor sends bold message on goldFiscal Q1 sales supercharged to $13.64 billion (+21% sequential, +57% year over year). Moreover, gross margin surged to 56%, up from 44.7%, with GAAP net income climbing to $5.24 billion.As we look ahead, things are only going to get more lucrative.DRAM contract prices are forecasted to rise 90-95% quarter over quarter in Q1 2026, per TrendForce. Also, NAND prices could skyrocket by 55% to 60%, while PC DRAM pricing may jump by more than 100% quarter over quarter.Additionally, Micron is leaning in with massive capex, with a roughly $4.5 billion per-quarter baseline for 2026, without a substantial impact on inventories. Renaissance cashes in on Nvidia’s runRenaissance trimmed hard on the AI trade, and perhaps the standout cut was Nvidia.The fund decreased its stake in Nvidia by nearly $887 million, with the position dropping from $1.05 billion at the end of Q3 to just $162.5 million at year-end in a major re-balance.Clearly, Nvidia has been a poster child of the AI trade and has been on a killer run over the past three years.The stock reached an all-time closing high of $207.03 in late October 2025, finishing the year at $186.50. By mid-February 2026, it still carries an eye-popping $4.5 trillion market cap, trading at more than 45 times non-GAAP earnings (trailing-12-months).On paper, it seems more like portfolio hygiene, where Renaissance is keeping exposure to the hotter trade, harvesting gains, and redeploying capital where pricing power is still early in the piece.Related: JPMorgan doubles down on S&P 500 target for one key reason